The present invention relates to a stirring device for stirring liquid in a rotating container, and more particularly, concerns such a stirring device which is operable with such a rotating container due to gravity inducement.
Rotatable containers which are employed in solid surface cell culture production are commonly referred to as "roller bottles." These bottles, made of glass, plastic or other suitable material, have their interior surfaces treated for the culturing of cells. Roller bottles, and the tissue culturing processes, are generally performed within the laboratory or other suitable locations.
In utilizing the roller bottle technique for culturing of cells, the preferably cylindrically shaped bottle is placed on its rounded peripheral surface between two rolling bars which impart rotary motion to the bottle. A liquid growth medium is placed inside the bottle, generally so that the liquid medium does not reach the level of the bottle opening. Upon rotation of the bottle, the liquid growth medium contacts the treated interior surfaces of the bottle in a constant wetting motion. This type of motion is conducive to the growth of cells on the interior surface of the bottle.
In many instances, the nature of the cells to be cultured or the cell culture system necessitates the use of a stirring device inside the liquid medium. This is the case of cells growing in suspension or cells attached to microcarrier beads that are suspended inside the liquid medium. Such a stirring device has to impart some stirring motion to the liquid which is different from the rotary motion of the liquid caused by the rotating roller bottles. In other words, a stirring device would move faster or slower than the rotating bottle in order to cause this stirring movement.
Heretofore, no known stirring devices have been adapted to a roller bottle. Existing stirring devices are placed inside a non-movable container. Such items as spinner flasks are far from being ideal as they create problems when they are placed in an incubator. For instance, many of these devices generate heat, and when placed inside an incubator increase its temperature, thereby making it necessary to recalibrate the incubator temperature control. Furthermore, the known stirring devices have flat bottoms which are inappropriate for keeping the cells in motion. Moreover, these known stirring devices may add expense to the assembly and its operation. Accordingly, the present invention is directed to overcoming these deficiencies in the heretofore known stirring devices and to provide a new device that stirs the liquid growth medium inside a liquid container such as a rotating roller bottle.